动态规则-70. 爬楼梯

题目

class Solution {
public:
    int climbStairs(int n) {
        //和斐波那契数列的解法一致
        int onestep=1;
        int twostep=1;
        int res=1;
        for(int i=2;i<=n;i++)
        {
            res=onestep+twostep;
            onestep=twostep;
            twostep=res;
        }
        return res;
    }
};